Flexible electrode



May 29, 1951 L. JENSEN 2,555,037

FLEXIBLE ELECTRODE Filed June 21, 1949 Iii/ 7. 1. Er /y. 2.

INVENTOR. 5 62 4 L e e Jensen his A tt-o ne y Patented May 29] 11751 UNITED STATES PATENT OFFICE FLEXIBLE ELECTRODE- Lee Jensen, Chattanooga, Tenn.

Application June 21, 1949, Serial No. 100,447

3 Claims.

This invention relates to electro-medical apparatus and more particularly to an electrode capable of conforming to the contour of an area of the anatomy and establishing good electrical contact therewith.

In making electro-cardiograms good electrical contact between the skin of the patient and the electro-cardiograph leads is essential to insure correct readings and it is also necessary that the electrical resistance of the skin of the patient be reduced to a minimum. As in making electrocardiograms. the practice of electro-therapy also demands good electrical contact between the electrodes. employed and the skin of the patient as well as a breaking down of the electrical resistance of the skin. One of the most satisfactory methods of breaking down such electrical resistance of the skin is through the application of moist heat to the area, and in electro-therapy in particular it is important, when applying polarized low voltage currents, that ample moisture be present owing to the fact that when any part of an electrode dries out a burnfrequentlyresults.

A major object of this invention is to prepare an area of the skin of a patient to transmit electrical impulses and to preserve the conductivity of the area throughout the duration of the application of theelectro thereto.

Another object is to insure good electrical contact between an area of the anatomy of a patent and electro-medical apparatus and further to obtain even distribution and transmission of electrical energy between the area and the electrode.

A further object is to enable the electrode to be shaped to the contour of the area to which it is; applied, and automatically to deposit on the skin. of the patient a layer of electrode paste.

Another and more specific object is to preserve throughout the duration of a treatmentv of a patient, warmth. and moisture. conditions adjacent the skin such as will avoid effecting a burn.

A further and more specific object is to facilitate the introduction of the electrode paste into the envelope as, the volume. of the paste in the envelope becomes diminished through. use.

The above and other objects may be attained by employing this invention which embodies among its features a paste possessing good electrical conductivity and comprising water containing a colloidal suspension of an inert hydrophilic material and an envelope. of flexible. material at least one wall of which possesses a porosity that will permit a portion of the paste to ooze through and into intimate contact with the area of treatment of the anatomy of a patient.

Other features include a filling aperture opening through a wall of the envelope through which electrode paste may be introduced to replenish the paste which oozes through the envelope.

Still other features include an internally screw threaded ring carried by the envelope in which may be removably engaged a threaded closure plug of conducting material, or the threaded nipple of a conventional collapsible tube.

In the drawings,

Figure l is a plan view of an electrode embodying the features of this invention,

Figure 2 is a side view of the electrode disclosed in Figure 1, showing the conductor plug removed and a conventional collapsible tube coupled to the conductor ring surrounding the filling open- 111g,

Figure 3 is an enlarged sectional view taken substantially along the line 3-3 of Figure 1,

Figure 4 is a fragmentary sectional view taken substantially along the line 44 of Figure 3, and

Figure 5 is a side view partly in section of a modified form of electrode embodying the features of this invention.

Referring to the drawings in detail. this improved electrode comprises an envelope designated generally I!) which in the preferred form of. the invention is formed of a single strip of flexible fabric l2 which is folded at I4 and has opposite side edges I6 joined together by concealed stitches to form a hollow sack. The edges 3 of the fabric strip l2 remote from the fold M are joined together by a row of stitches ill to form a completely closed envelope of substantially rectangular form, though it is to be understood that any other suitable geometrical shape may be employed.

In the preferred form of the invention one of the side walls of the envelope EU has opening therethrough a filling aperture 22 and seated against the inner side of saidwall in concentric relation to the aperture 22 is a conductor ring 24 having formed therein an annular row of internally screw threaded openings 25 which align with an annular row of openings 28 formed in the wall having the filling aperture 22. A clamping ring 30 of conducting material is seated on the wall having the filling aperture '22 therein and extending through an annular row of openings 32 in the ring 3!] are clamping screws 34 which enter the threaded. openings. 26 eifectively to clamp the fabric i2 between the rings 2!! and 30. The inner periphery of. the. ring 30. is internally screw threaded as at 36 to receive the threaded end 38 of a closure plug 40 or the threaded nipple 42 of a conventional collapsible tube 45.

The closure plug 40 is preferably formed of a conducting material and is provided adjacent the end remote from the threads 38 with a transversely extending opening 46 for the reception of the conductor of conventional electro-medical apparatus such as an electro-cardiograph or electro-therapeutic apparatus. Extending laterally into the body of the plug 40 and opening into the opening 46 is an internally screw threaded bore 48 in which is received a pointed set screw 50.

In the preferred form of the invention the fabric from which the envelope is made is a porous woven fabric possessing a thread count of 64x96 per square inch though I have found that fabrics having a mesh size of not less than 200 mesh per square inch are serviceable. It is preferred, however, that the porosity of the envelope as a whole be such as to render it easily penetrable by water and further that at least that portion of the envelope which contacts the area of the anatomy under treatment, be sufficiently porous as to permit a part of the colloidal suspensions forming the filling to ooze through the envelope and into intimate contact with the portion of the anatomy to which the electrode is applied.

In the modified form of the invention illustrated in Figure the envelope designated generally 52 is formed of a sheet 54 of flexible material such as the fabric above described having a porosity that will permit the passage therethrough of a portion of the filling paste, and a sheet 56 of flexible material which may be less porous or even without porosity. These sheets are joined at their edges in any suitable manner to form the complete envelope and the sheet 56 is formed with a filling aperture (not shown) which is surrounded by a ring structure designated generally 58 such as above described. The filling aperture is closed by a conductor plug 60 which corresponds in all respects to the plug 40 and when the plug 60 is removed the threaded nipple 42 of the collapsible tube 44 may be introduced into the ring structure 58 to enable additional electrode paste to be introduced into the envelope 52.

The envelope H) or 52 is filled with a suitable electrode paste 62 which comprises water containing a colloidal suspension of an inert hydrophilic material. If so desired an electrolyte such as salt may be added to the paste in order to increase the electrical conductivity thereof, and where necessary any suitable stabilizer may be introduced into the compound to preserve the stability thereof.

Experiments have taught that there are many substances both of organic and inorganic origin that may be used in producing flexible electrodes in accordance with this invention and disclosed below are samples of pastes possessing the necessary characteristics.

Common organic substances that I have used are: Acacia, agar, casein, chondus, tragacanth, gelatin and algin of the type sold under the trade name Kelgin.

A typical organic electrode paste which is suitable for this purpose is as follows:

Parts Water 4 Gum tragacanth (finely powdered) 1 Glycerin 4 In preparing the paste the powdered gum tragacanth and glycerin are mixed thoroughly, allowed to stand for forty-eight hours. The water is then added and the mixture is stirred until a homogenous, thick paste results. The paste thus produced is allowed to stand for several days. If so desired, one percent boric acid may be added as a preservative and after the base has been completed an electrolyte, such as sodium chloride, may be added to improve the electrical conductivity of the mass. The amount of electrolyte employed may vary anywhere from 25% by weight up to 100% by weight of the mass according to the requirements of the user.

Among the inorganic substances that have been found useful in making an electrode paste suitable for use as a filler for this electrode are, gels of alumina, magnesia, silica, and their combinations, such as bentonites, and a composition sold by R. T. Vanderbilt Company under the trade name, Veegum.

An example of one such inorganic electrode paste comprising alumina gel of the type sold by the Aluminum Company of America and identified as H is as follows:

Alumina gel parts 3 Stabilizer do 1 Electrolyte per cent by weight 25 to As the stabilizer in the above compound, I employ a gel composed of 20% bentonite and 80% water, and for the electrolyte I prefer sodium chloride.

Other inorganic electrode pastes having the desired properties may be made in a like manner by substituting for the alumina gel, gels of silica or magnesia, or gels of silica, alumina and magnesia and compounding substantially as above.

In the preferred form of the invention, however, I employ a simple composition comprising bentonite (True-Wyoming type) and water to which an electrolyte may be added. The ingredients are used in the following proportions:

Parts Bentonite 15 to 20 Distilled water 100 In preparing the electrode paste, I employ bentonite which has been prepared so as to have a particle size lying between 200 mesh per square inch and 1000 mesh per square inch. The bentonite so prepared is introduced into the water and stirred thoroughly. The mixture is then allowed to set for twenty-four hours and again thoroughly mixed. This produces a viscous colloidal suspension having a paste-like consistency similar to that of petrolatum, and an electrical conductivity which exceeds that of the water by about nine times. When increased electrical conductivity is desired, I add to the paste thus formed a suitable electrolyte, such as sodium chloride, in an amount ranging from 25% up to 200% by weight of the paste and in some instances a plasticizer such as glycerin. I have found when glycerin is employed as the plasticizer up to 1% is usually adequate.

What is claimed is: r

1. As a new article of manufacture capable of effecting good electrical contact between a portion of the anatomy of a patient and electromedical apparatus, a flexible electrode capable of being shaped to the contour of a portion of the anatomy, said electrode comprising a stable paste formed of water containing a' colloidal suspension of an inert hydrophilic material, an

envelope of flexible material enclosing said paste, at least one wall of said envelope being porous whereby upon exerting pressure on the envelope a portion of the paste will pass therethrough and into intimate contact with the portion of the anatomy to the contour of which the electrode conforms, and a conductor extending through a wall of the envelope and contacting said paste for conducting electrical energy through said envelope.

2. As a new article of manufacture capable of effecting good electrical contact between a portion of the anatomy of a patient and electromedical apparatus, a flexible electrode capable of being shaped to the contour of a portion of the anatomy, said electrode comprising a stable paste formed of water containing a colloidal suspension of an inert hydrophilic material, an envelope of flexible material enclosing said paste, at least one wall of said envelope being porous whereby upon exerting pressure on the envelope a portion of the paste will pass therethrough and into intimate contact with the portion of the anatomy to the contour of which the electrode conforms, said envelope having a filling aperture opening through one wall thereof, and an internally screw threaded ring carried by the envelope in concentric relation to the filling aperture for receiving a threaded closure plug or the threaded nipple of a conventional collapsible tube.

3. As a new article of manufacture capable of effecting good electrical contact between a portion of the anatomy of a patient and electromedical apparatus, a flexible electrode capable of being shaped to the contour of a portion of the anatomy, said electrode comprising a stable paste formed of water containing a colloidal suspension of an inert hydrophilic material, an envelope of flexible material enclosing said paste, at least one wall of said envelope being porous 6 whereby upon exerting pressure on the envelope a portion of the paste will pass therethrough and into intimate contact with the portion of of the anatomy to the contour of which the electrode conforms, said envelope having a filling aperture opening through one wall thereof, an internally screw threaded ring of conducting material carried by the envelope in concentric relation to the filling aperture, a conductor extending through the ring and the wall of the envelope and contacting said paste for conducting electrical energy through said envelope and a closure plug of electrically conductive material removably threaded into the ring.

LEE JENSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,076,210 Kerr et al. Oct. 21, 1913 1,480,353 Wappler Jan. 8, 1924 1,528,908 Bleininger Mar. 10, 1925 1,583,087 Morse May 4, 1926 1,585,104 Montgomery May 18, 1926 1,769,090 Wappler et a1. July 1, 1930 1,889,271 Zerne Nov. 29, 1932 FOREIGN PATENTS Number Country Date 44,432 Switzerland July 6, 1908 59,458 Austria June 10, 1913 OTHER REFERENCES Ad. of the American Colloid Co., 1 page; recd in Div. in 1936.

Catalog 14, May 1, 1924, of H. G. Fisher 8; Co., Inc., 2333 Wabansia Avenue, Chicago, Illinois; page 17. Copy in Div. 55. 

